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Anna B. Comstock

The Dodder

Teacher's Story

If Sinbad's "Old Man of the Sea" had been also a sneak thief, then we might well liken him to dodder. There is an opportunity for an excellent moral lesson connected with the study of dodder and its underhand ways. When a plant ceases to be self-supporting, when it gets its own living from the food made by other plants for their own sustenance, it loses its own power of food-making; and the dodder is an excellent example of the inevitable punishment for "sponging" a living. The dodder has no leaves of its own for it does not need to manufacture food nor to digest it. Its dull yellow stems reach out in long tendrils, swayed by every breeze, until they come in contact with some other plant to which they at once make fast. One of these tendrils seizes its victim plant as a serpent winds its prey, except that it always winds in the same direction—it passes under from the right side and over from the left. Who knows whether the serpents are always so methodical! After dodder gets its hold, little projections appear upon its coiled stems, which look like the prolegs of a caterpillar; but they are not legs, they are suckers, worse than those of the devil-fish; for the latter uses its suckers only to hold fast its prey; but the dodder uses its suckers to penetrate the bark of its victim, and reach down to the sap channels where they may, vampirelike, suck the blood from their victims, or rather the matured sap which is flowing from the leaves to the growing points of the host plant. Not having anything else to do, dodder devotes its energies to the producing of seeds, in order to do more mischief. The species which attack clover and other farm crops seem to manage to get their seeds harvested with the rest; and the farmer who does not know how to test his clover seed for impurities, sows with it the seeds of its enemy.


[Illustration]

Dodder in blossom.

Photo by Cyrus Crosby.

The dodder flowers are small, globular and crowded together. The calyx has five lobes; the corolla is globular, with five little lobes around its margin and a stamen set in each notch. A few of the species have a four-lobed calyx and corolla; but however many the lobes, the flowers are shiftless looking and are yellowish or greenish white; despite its shiftless appearance, however, each flower manages to mature four perfectly good, plump seeds.

There are, according to Gray, nine species of dodder more or less common in America. Some of the species, among which is the flax dodder, live only upon certain other species of plant life, while others take almost anything that comes within reach. Where it flourishes, it grows so abundantly that it makes large yellow patches in fields, completely choking out the leaves of its victims.

Lesson CXXX

The Dodder

Leading thought—There are some plants which not only depend upon other plants to hold them up, but they suck the life-juice from these plants and thus they steal their living.


Method—Bring in dodder with the host plant for the pupils to study in the schoolroom, and ask them to observe afterwards the deadly work of this parasite in the field.


Observations—

1. What is the color of the stem? In which direction does it wind?

2. How is the stem fastened to the host plant? Tear off these suckers and examine the place where they were attached with a lens, and note if they enter into the stem of the host plant.

3. How does the dodder get hold of its victim? Has the dodder any leaves of its own? How can it get along and grow without leaves?

4. How do the flowers look through a lens? Are there many flowers? Can you see the petal lobes and the stamens?

5. How many seeds does each flower develop? How do the seeds look? In what way are they a danger to our agriculture?


I should also avoid the information method. It does a child little good merely to tell him matters of fact. The facts are not central to him and he must retain them by a process of sheer memory; and in order that the teacher may know whether he remembers, the recitation is employed,—re-cite, to tell over again. The educational processes of my younger days were mostly of this order,—the book or the teacher told, I re-told, but the results were always modified by an unpredictable coefficient of evaporation. Good teachers now question the child to discover what he has found out or what he feels, or to suggest what further steps may be taken, and not to mark him on what he remembers. In other words, the present-day process is to set the pupil independently at work, whether he is young or old, and the information-leaflet or lesson does not do this. Of course, it is necessary to give some information, but chiefly for the purpose of putting the pupil in the way of acquiring for himself and to answer his natural inquiries; but information-giving about nature subjects is not nature-study.

—L. H. Bailey in "The Outlook to Nature."